This research has developed a fabricating process of thin-strain sensor by utilizing wafer-level-packaging (WLP) techniques. The thickness of sensor makes thinner, its performance is able to highly increase. However, the thinner sensor was fragile, and so it was difficult to handle in post processes. Thus, a thin sensor with lid by utilizing WLP techniques, which is tough to break even when handled, is proposed in this research. More than 250-mm-deep grooves were fabricated around the lid by deep reactive ion etching. After the lid substrate was bonded on the sensor substrate with a resin, the sensor and lid substrates were respectively polished to 50 µm and 200 µm thickness. The lids were released along the grooves, and the 50-mm-thick strain sensors were able to be fabricated by utilizing WLP techniques. This sensor was used as a diaphragm to measure pressure. The sensors were assembled on a stainless steel housing without breakage. The performance of developed sensor was almost showed with a conventional pressure sensor.

We have developed a multi-function scanning probe microscopy (Multi-SPM) system that integrates FM-AFM/KFM/A-MFM techniques for comprehensive imaging of current path within power semiconductor devices. This advanced Multi-SPM setup enables concurrent visualization of surface morphology, surface potential, and magnetic field intensity gradients. During both non-conduction and conduction of DC current, we were able to simultaneously investigate these parameters in the same spatial region. Notably, the magnetic field intensity gradient distribution accurately captured the static magnetic field generated by the DC current flow. Particular interest is the dynamic variation in intensity and polarity of the H_z component of the magnetic field gradient distribution in response to the conduction of current and its direction. Based on these findings, we can confidently affirm that A-MFM effectively enables the observation of magnetic fields surrounding direct current path.

In this study, we focused on acoustic emissions (AE) as a quantitative evaluation method of algae culture conditions. Since algae produce oxygen during photosynthesis, we thought it would be possible to detect foamed AE. Therefore, AE measurements were made in algae culture tanks and AE measurements were made using an electret sensor (ECS) to investigate the possibility of evaluating algae culture conditions. AE was detected more frequently when the lighting of the thermostatic chamber was turned on, suggesting that AE derived from algal photosynthesis could be detected. Furthermore, there was a positive correlation between the dry weight measured at the same time and the number of AEs detected, so it is expected that AE measurements using ECS can be used to monitor algae culture conditions.